Clear Resin

Clear resin is a liquid photopolymer for LCD/MSLA and DLP printing that cures under 405 nm UV light and, once set, yields nearly colorless, transparent parts. Unlike regular resins it is specially stabilized against yellowing and keeps its color clean. Straight out of the vat a part looks cloudy and matte because of the layer lines and surface microtexture — true optical clarity is reached by sanding and a clear coat applied after printing.

What it is good for

• Lenses, light guides and optical elements where light transmission matters
• Lighting housings and diffusers, lampshades and backlight panels
• Exhibition and demo models that show their inner structure
• Jewelry and design master models, clear nameplates and inserts
• Transparent enclosures for electronics and devices for visual inspection

Where NOT to use it

• Impact-resistant or heavily loaded parts — cured photopolymer is brittle and cracks under impact
• Parts left permanently in sunlight or bright light — even a stabilized material yellows and clouds over time under UV
• Finished transparent parts without post-processing — without sanding and a clear coat the part stays cloudy
• Precision optics without finishing — layer lines and matrix pixels distort the image, so manual polishing is required

How to print

• Print type: LCD/MSLA or DLP, 405 nm curing wavelength
• Layer height: 0.025–0.05 mm — thin layers leave fewer visible lines and give higher clarity
• Layer exposure: roughly 2–4 s on a mono LCD; dial in the exact value by calibration and the maker's recommendation
• Thick clear walls need more exposure than thin ones — a solid volume takes longer to cure all the way through
• Room temperature: keep the room warm (about 22–28 °C) — cold resin thickens and cures poorly
• Adhesion: a flat, leveled build plate and properly set bottom-layer exposure
• Washing: isopropyl alcohol or ethanol, gently and briefly so the surface does not cloud
• Post-curing: 405 nm UV in short doses at room temperature — over-curing yellows the material

Clarity: how to achieve it

• Thickness: make clear walls solid and reasonably thick (about 3–4 mm) with no internal voids — bubbles and cavities scatter light
• Orientation: position the part so there are as few layers as possible along the viewing direction — layer lines blur the image
• Sanding: work the surface step by step from coarse to fine grit (roughly 400 up to 2000–3000 and beyond), removing every layer line and scratch
• Clear coat or wetting: after sanding apply a clear acrylic varnish (or a thin film of clear resin) — it fills the microtexture and restores optical clarity
• Post-curing: do the final cure in short doses at room temperature and do not over-cure — otherwise the part yellows

Pros and cons

• After polishing and a clear coat it yields crystal-clear parts
• Stabilized against yellowing — holds a clean color longer than ordinary resin
• High detail and a smooth surface typical of resin printing
• Lets you print optics, light guides and backlighting that filaments cannot do

• Without post-processing the part is cloudy — it needs labor-intensive sanding and coating
• Brittle: the cured material handles impact and bending poorly
• Yellows from over-curing and over time under bright UV
• Thick walls need more exposure and careful calibration
• Liquid photopolymer is toxic and messy — gloves, glasses and ventilation are required